A Cereal Company Exec Has Lost $218 Million Of His Own Money On Herbalife

William "Bill" Stiritz. Reuters/ Brendan McDermid CORRECTION: An earlier version of this post identified William Stiritz as the CEO of Post Holdings. Stiritz stepped down as CEO on November 1, 2014 to become executive chairman of the company. @BarbarianCapital was the first to point it out.

William "Bill" Stiritz — Herbalife's largest shareholder — has gotten absolutely annihilated on his stake in the nutritional company.

According to our estimates, he has lost about $218.8 million on his investment so far.

Herbalife — a multilevel marketing firm that sells nutrition products like weight-loss shakes and vitamins— has been at the center of a hedge fund war for over two years.

Activist investor Bill Ackman, the CEO of Pershing Square Capital, publicly announced in December 2012 that he was shorting the company to $0.

Ackman's thesis is that the company operates as a "pyramid scheme" that targets poor people. He believes regulators, specifically the Federal Trade Commission, will shut the company down. (The FTC opened an investigation in March 2014).

After Ackman made his short public, numerous hedge fund managers, most notably Carl Icahn, piled on by going long the stock. In the months following Ackman's initial presentation, share of Herbalife skyrocketed and Ackman rocked up millions in paper losses.

Ackman is now back in the money on his position as the stock has declined in recent months.

And those who were long are feeling the pain.

Stiritz, 79, has racked up hundreds of millions in paper losses, according to our calculations.

On Sept. 3, 2013, Stiritz disclosed a huge long Herbalife position. At the time, Stiritz owned 5,382,362 shares, or a 5.22% stake. We estimated then that Stiritz's Herbalife stake was worth about $322 million. The stock closed at $59.90 the day he disclosed that position.

On Nov. 18, 2013, (when Herbalife was at $67.20) and again on Jan. 29, 2014, (when Herbalife was at $62.82), Stiritz added to his position. He most recently held 7,484,804 shares, or an 8.15% stake, data compiled by Bloomberg shows.

Since Stiritz first reported the position, shares of Herbalife have slumped more than 46%. The stock was trading down 2.5% on Tuesday morning at $32.12 per share.

Using the closing price of the days on which Stiritz disclosed his stakes, we calculate that he has lost an estimated $218.8 million on his Herbalife investment so far.

The second-largest shareholder is Herbalife's CEO Michael Johnson, and he owns just over 1.38 million shares.

We don't know Stiritz's personal net worth. He's not mentioned on the billionaire lists from either Forbes or Bloomberg.

Stiritz is Post Holdings' largest individual shareholder, with approximately 369,662 shares, Bloomberg data shows. His Post stake is worth just over $15.1 million based on Monday's closing price.